The Russian Foreign Ministry accuses US diplomats of trying to access restricted military areas and will submit formal protests.

"US military diplomats often ignore Russian demand notifications and try to enter restricted areas. We urge Washington to adhere to diplomatic standards," Russian Foreign Ministry spokeswoman Maria Zakharova speaking at a press conference today in Moscow.

The Kremlin earlier said that there were strict rules for sensitive military subjects that people must follow.

The Russian statement comes after three US diplomatic officials visiting Russia were taken off the ship on October 14 in Severodvinsk because they were not allowed to go to the site of the nuclear submarine. Russian officials checked the papers on three people, including navy and defense attaches, and released them. They are suspected of violating rules against foreigners visiting restricted areas.

The US says its officials are on an official visit and have informed the Russian authorities of the schedule and proper action.

The Russian Foreign Ministry confirmed in a statement to the media that this was "an official visit and the US side informed the Defense Ministry in advance of the plan". However, Moscow said that the diplomats intended to go to Arkhangelsk but they boarded the ship to Severodvinsk. These two places are about 30 km apart.

Severodvinsk is an Arctic port with a nuclear submarine factory, which only allows foreigners to visit if they have a special permit. Severodvinsk is located near the shooting range in Nyonoksa. On August 8, 5 people were killed in a rocket engine test here.